Discharge device with water cooled baffle



March 30, 1943. D.y E. MARSHALL EfrAL DISCHARGE DEVICE WITH WATER COLED BFFLEv Filed Sept. 26, 1 940` 'Allllil Patented Mar. 30, 1943 DISCHARGE DEVICE WITH WATER COOLED BAFFLE Donald E. Marshall, Allwood, and William J.

Knochel, Irvington, N. J., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application September 26, 1940, Serial No. 358,474L

l 11 Claims.

Our invention relates to discharge devices,

'andespecially to discharge devices utilizing a metal casing. f

An objectv of the invention is to prevent arc back in mercury pool discharge devices.

Another object of the invention is to provide a cooled bailie between the cathode and anode of a discharge device sufliciently restricted to prevent arc back and yet suiciently open to permit large current flow in the discharge path.

A still further object of the invention is to provide an easily assembled metal casing for a mercury pool discharge device.

Other objects and advantages of the invention will be apparent from the following descrip- 'tion' and drawing wherein:

Fig. 1 is a view, principally in cross section, of a discharge device embodying a preferred form of our invention.

Fig. 2 is a view on line II-II of Fig. 1.

Fig. 3 is a View on lines III-III of Fig. l.

Fig. 4 is a view on lines IV-IV of Fig. 1.

Fig. 5 is a cross-sectional view through a baf- Iie illustrated in Fig. 1.

Fig. 6 is a bottom view on lines VI-VI of Fig. 5.

Fig. 7 is a cross-sectional view illustrating a modification of the casing on a plane similar to Fig. 4.

vietitjrn is to prevent arc back in mercury pool devices,` andparticularly inthe type of device utilizing a metal casing. We accomplish this ob- `iectl by placing a water-cooled baille intermediate the mercury pool and the cathode, and we also preferably place a second baille to intercept all' straight line paths between the mercury pool andthe anode through the water-cooled baffle.

The water-cooled bafe must be sufciently 4open to permit suicient current to flow in the discharge path between the mercury pool and the anode. The water-cooled baiiie provides a 'difference of vapor 'pressure around the anode,

and in the space about the opening in the baiiie so that there will be no danger of an arc back starting in the anode region. In addition to this general object, we haveA also designed a very eiiicient water-cooled metal casing, and one that is easily assembled in quantity.

The preferred embodiment of our invention is disclosed in Fig. 1 in which a tubular inner casing I0, preferably of stainless steel,- is closed at its lower end by a dish-shaped plate II, alsoof stainless or cold-rolled steel, having its downwardly turned flange I2 welded to the casing I0. The lower end of the casing IIl is bent out just beyond the edge of the lower ange I2 to an edge I3 which is 'welded in turn to an outer casing I4, preferably of stainless steel, to form a space I5 for the -passage of a cooling uid, such a water, between the two casings.

The upper portion of the casing I0 also has a bent-out portion at I5, which is welded to the upper end I'I of the outer vcasing I4. At the lower end of the casing I0 is an inlet I8 for the cooling uid, and in the upper portion of the casing I0 'is an outlet I9 for this.V cooling uid.

Helical vanes or wires 20 pass around the inner casing and iill the space between the two casings in order toprovide a circular path" about the inner casing from the inlet I8 to the outlet I9 for the'cooling fluid.

Thev dish-shaped member I I, in combination with the adjacent edge of the inner casing'l, provides a location for the mercury pool cath"- ode 2l. A ring 22, of quartz or molybdenum, has its periphery of one circular edge secured by any suitable fastening means 23, and the portion of the ring extending about the mercury Vprovides a restricted portion of the mercury pool in the central portion in the bottom of the device.

The standard 24, preferably of cold-rolled steel, is attached to the bottom plate II and sup'- ports`a baffle 25, preferably of graphite. or :of some other materiaLwith a carbon or carbonized surface. VThel particular form of ,bae we #prefer is illustrated in Figs..5 and 6, which form'has va plurality of openings 2'! in the underside 28. These openings pass part way through the b-afile structure and then turn at an'angle to opening 29 in the upper curved side 30 of the baie;

It will Abev noted in Fig'. 5 that there is no straight line path from the openings 21 and the undersideto the opening 29 in the upper portion thereof, A shield 3|, preferably molybdenum, encloses the lower .portion of the standard 24 supportingthe baifle 25. A pointed makealive device 32, more clearly disclosed in Fig. 10, has its tapered point inserted inthe mercury. This igniting device is of high resistance material, preferably of boron carbide, which does not amalgamate with mercury.

Thev upper,` portion of; this igniting device is supported by an arm 33, which is in turn supported by a standard 34 passing through an opening in the lower plate. This standard has a cupshaped flange 35 sealed to a ring 36 of borosilicate glass which in turn is sealed to a metal eyelet 31, preferably of cobalt-nickel-iron alloy sold under the trade name of Kovan secured to the bottom plate 23, as by welding. The ange 35 is also preferably of this cobalt-nickel-iron alloy. The portion about the seal of the eyelet 31, glass 36 and conductor 34 is preferably protected by a shield 38 of metal, preferably molybdenum or cold-rolled steel. The shield .38 protects the insulating material or glass 36 during heat treatment. The slot 38' permits the shield 38 to be lowered over the make-alive structure and welded or brazed to the bottom plate. Y

The casing ||J preferably has two opposite openings 40 and 4 l located slightly above the position of the baiile 25. These two openings 4D and 4I provide the entrance from the space vbetween the casings for the cooling fluid to enter a water-cooled baflle, whose preferred form is illustrated in Figs. 1 and 4.

The baffle design, as disclosed in Fig. 1, is preferably wedge-shaped in cross section to extend inwardly in annular form from the inner surface of the casing l0. This baille is preferably made of two headers 42 and 43, having an annular flange 45 welded to the casing l0, and then having a dish-shaped extension 46 sloping towards one another to meet in an annular edge 41 about a central opening 48. The two edges 41 are welded together.

In Fig. 2 is disclosed the portion of the directing vanes 20 adjacent the opening 40 to the bafile 44. A semi-circular vane 49 surrounds part of the casing Ill and has a downwardly curved portion 50 to prevent the continuation of the ow of liquid vabout the casing and to force this liquid into 'the opening 4B. Another semi-circular vane 5| has a curved end 52 about the opening 4| to force the cooling fluid as it leaves the'ballle 44 to continue its helical path about the casing.

In the cross section of Fig. 4 is illustrated the path of the cooling fluid entering the opening 40 of the wedge-shaped baffle 44 and passing around the inner portions 53 and 54 to the exit .port 4| on the other side of the casing.

A modication of this construction is illustrated in Fig. 7 where the two ports 55 and 56 are located upon one side of the casing, and the cooling medium enters the one port 55 and passes completely around the inner portion 51 of the wedgeshaped baille and leaves at the exit port 56 to continue its curving cool path about the inner casing.

In the upper portion of the casing I9 is located the anode 60, preferably of graphite or carbon, located on a shaft 6|, connected to a shaft 63 of smaller diameter, forming an exterior anode connection. A dish-shaped member 84 has its bottom perforated for the shaft 63 and is welded or brazed to the broad top of the shaft 6|. This member 64 is preferably of nickel-cobalt-iron alloy sold under the trade name Kovan The upper edge of this. member is preferably bent over and downward to seal into the edge of a cylinder of borosilicate glass 65. 'Ihe other edge of this cylinder is sealed to the edge of a cylinder 62 of nickel-cobalt-iron alloy sold under the trade `name Kovar.

having a central annular flange 61, welded or f brazed (silver or copper, or both) to the lower edge of the tubular member 62. An outer annular flange 68 is likewise welded or brazed to the inner edge of the casing I6. The upper end of the outwardly extended conductor 63 has a nut 63 upon which is screwed the air-cooled iins 10.

The device may be supported on a standard 1| having a supporting plate 12, welded to the bottom plate closing the lower portion of the casing. If desired, the plate 12 may be spaced from the cathode plate I, and the space intermediate the two plates connected to the inlet port I8 for cooling the plate H, as well as the inner tubular casing I0.

In Figs. 8 and 9 we have illustrated a modification 8D of the baiile illustrated in Figs. 5 and 6. This baffle has a central portion 8|, supporting two practically parallel discs 82 and 83, having a plurality of openingsl therethrough. The openings 84 on the lower disc 82, as illustrated in the full lines in Fig. 9, are out of alignment with the openings 85 in the upper disc 83, as Yillustrated by the dotted lines in Fig. 9. There is, accordingly, no straight line path for the discharge through the baffle in these figures.

In Fig. l it will be noted that the combination of the water-cooled baffle 44 and the baffle 25 intersects all straight line paths between the surface of the mercury 2| and the anode 60. The cooling eiect of the water-cooled baffle 44 condenses the mercury vapor as it passes around the baffle 25 to approach the opening 48 to the anode portion of the device. The result of this cooling is that the vapor pressure in the anode chamber in the upper portion of the device is so low that no backre will start from this region of low vapor pressure.v On the other hand, the space between the two bailles is suiciently open so that there will be no limiting effect on the amount of current in the discharge path between the cathode and the anode.

It is also to be pointed out that the form of the header 66 `results in extreme simplicity of design and easiness of assemblage. The shielding of the make-alive provides special protection for the insulation 36.

It is apparent that many modifications may be made in the preferred structure illustrated and, accordingly, we desire only such limitations to be imposed upon our invention as are necessitated by the spirit and scope of the following claims.

We claim:

l. A discharge device comprising a cylindrical metal envelope, a pool cathode therein, an anode spaced above said cathode, an annular hollow extension from the inner cylindrical wall of said envelope extending into the space between said cathode and anode, and means for passing a cooling fluid through said hollow extension.

2.A discharge device comprising a metal envelope, a pool cathode therein, an anode spaced above said cathode, a hollow casing extending in a wedge shape laterally from the side of the metal envelope and closing off all but a central opening between the cathode and anode, and means for passing a cooling fluid through said wedge-shaped casing.

3. A discharge device comprising a metal envelope, an anode in the upper portion of said envelope, a pool cathode in the lower portion of said envelope, a hollow cooled baiile having spaced walls sealed peripherally to and forming part of said envelope, said baille closing the space between said cathode and anode except for a central opening, and a second baille between said pool cathode and said central opening.

4. A discharge device comprising a metal envelope, an anode in the upper portion of said envelope, a pool cathode in the lower portion of said envelope, a hollow cooled baffle having spaced walls sealed peripherally to and forming part of said envelope, said baille closing the space between said cathode and anode except for a central opening, and a second baille between said pool cathode and said central opening, said second baille intersecting all straight lines from the anode through said central opening in said cooled baille to said pool cathode.

5. A discharge device comprising a metal envelope, an anode in the upper portion of said envelope, a pool cathode in the lower portion of said envelope, a cooled baille closing the space between said cathode and anode except for a central opening, and a second baffle between said pool cathode and said central opening, said second baille having one set of openings on its underside communicating with another set of openings on its upper side, said second set of openings being out of alignment with said first set of openings.

6. A discharge device comprising a metal envelope, an anode in the upper portion of said envelope, a pool cathode in the lower portion of said envelope, a cooled baffle closing the space between said cathode and anode except for a central opening, and a second baille between said pool cathode and said central opening, said second baille having one set of openings on its underside communicating with another set of openings on its upper side, said second set of openings being out of alignment with said rst set of openings, said second baille also intersecting all straight lines from the anode through the central opening in said cooled baille to said pool cathode.

7. A discharge device comprising a cylindrical metal envelope, a pool cathode therein, an anode spaced above said cathode, an annular hollow extension from the inner cylindrical wall of said envelope extending into the space between said cathode and anode, a second envelope enclosing said first metal envelope, and inlet and outlet ports for a cooling uid to pass between said casings.

8. A discharge device comprising a cylindrical metal envelope, a pool cathode therein, an anode .spaced above said cathode, an annular hollow extension from the inner cylindrical wall of said envelope extending into the space between said cathode and anode, a second envelope enclosing said rst metal envelope, a port at one end of said outer envelope for a cooling fluid, means for directing said uid around the outer surface of said inner envelope, means directing said fluid through said annular hollow extension, and an exit port for said fluid at the other end of said envelope.

9. A discharge device comprising an envelope having double walls with space between said walls for a cooling medium, entrance and exit pipes at remote parts of said space for maintaining a flow of cooling medium throughout said space, and a double-wall transversely disposed baille in said envelope having a space between the walls of said baille for flow of cooling medium therebetween, said space between the envelope walls and said space between the baille walls being in communication one with the other.

10. A discharge device comprising an envelope having double walls with space between said walls for a cooling medium, entrance and exit pipes at remote parts of said space for maintaining a Ilow of cooling medium throughout said space, and a double-wall transversely disposed baille in said envelope having a space between the Walls of said baille for flow of cooling medium therebetween, said spaces being divided into a continuous flow channel from the entrance to the exit pipes.

11. A discharge device comprising an envelope having double walls with space between said walls for a cooling medium, .said space being partitioned and providing a circuitous ow passage with an entrance thereto and an exit therefrom and providing long distance of fluid travel therebetween, and a double-wall transversely disposed baille in said envelope having a space between the walls forming e, ow passage through said baille, said flow passage through the baille being interposed in the circuit of the flow passage of the double walls of the envelope.

DONALD E. MARSHALL. WILLIAM J. ICNOCHEL. 

